中文摘要：

在液膜厚度测量时,通过选取液态水吸收截面不同的两个波长可消除除液态水吸收以外的其他信号衰减所造成的影响,如轻微的光束转向现象。但该方法仍较难消除在液膜蒸发过程后期由于液膜收缩所造成剧烈的光束转向现象的影响。基于双波长可调谐半导体激光吸收光谱（TDLAS）技术测量透明石英玻璃板上液膜蒸发过程中膜厚的变化,并同时用图像法追踪液膜形状的变化,对剧烈的光束转向现象进行研究。在此基础上,通过在光电探测器前放置积分球,对已有的TDLAS液膜测量系统进行优化,以消除剧烈光束转向现象对膜厚测量的影响,并利用该系统分别测量了气流道内液膜形成过程和蒸发过程中液膜的厚度变化。

英文摘要：

Probing the liquid film at two wavelengths with different absorption cross-sections allows eliminating the effect of additional broadband signal losses, e.g. , minor beam steering. However, severe beam steering effects due to the shrinking of the liquid film at the end of the evaporation process can not be avoided. The effect is studied by measuring the film thickness on quartz plate during film evaporation process with two-color tunable diode laser absorption spectroscopy （TDLAS） method, and shadowgraphy images are simultaneously taken to track the change of film shape. Severe beam-steering effects are reduced in the developed two-line TDLAS film-measurement sensor by using an integrating sphere in front of the detector. The sensor is then applied to obtain the film thickness variation in the flow channel during the film build-up by impinging of water droplets and the evaporation of liquid film.